Hi Jennie,
The expansion mechanism that this buffet uses is the same that is used in expanding dining tables. So, there are techniques that can be applied. However, it would be a major redesign and re-engineering to use this as a starting point for a farmhouse-style expanding table. So, you’d need to be pretty confident in your design skills.
One point to consider in your redesign: Many farmhouse-style tables are trestle tables where the feet are connected by a beam, and that beam is sometimes the foundation for angled supports beneath the tabletop. Many (though certainly not all) expanding table designs feature legs that pull apart from one another when opening to accommodate the leaf, which couldn’t happen with a beam connecting the feet. There are expanding pedestal-style tables where the mechanism is attached to a central support and the tabletop separates while the central legs/base remain motionless. That type of design might make a better starting point for a makeover for farmhouse style. Sort of a faux trestle table where the “pedestal” is elongated to look like a trestle table? Hope that makes sense.